Pharmacokinetics of ciprofloxacin in Nile tilapia, Oreochromis niloticus

Abstract

Ciprofloxacin is a commonly used antibiotic in Bangladeshi aquaculture. However, the pharmacokinetic profile of ciprofloxacin in fish is not well studied. This study investigated the pharmacokinetics of ciprofloxacin in Nile tilapia (Oreochromis niloticus) following a single intraperitoneal administration at a dose of 50 mg/kg body weight. Blood samples from the fish were collected at 10 min and 1.5, 2.5, 5.0, and 6.0 h post administration. Serum ciprofloxacin concentrations were quantified using UFLC–MS/MS. Pharmacokinetic parameters were estimated using a non-compartmental analysis approach. The maximum serum concentration (C_max) of 28.60 ± 2.97 μg/mL was reached at a T_max of 10 min, which indicates rapid systemic absorption. In the present study, ciprofloxacin exhibited a moderate elimination phase, with an elimination rate constant (k) of 0.34 ± 0.01 h⁻¹ and a half-life (T½) of 2.03 ± 0.08 h. Moreover, the area under the concentration–time curve (AUC_t) was 77.80 ± 9.00 μg·h/mL, and the extrapolated AUC_i was 88.90 ± 10.50 μg·h/mL. The clearance (CL) of ciprofloxacin was 0.57 ± 0.06 L/h, and the volume of distribution (Vd) was 1.66 ± 0.15 L. From these findings, it can be suggested that ciprofloxacin demonstrates rapid absorption, adequate distribution, and efficient systemic clearance in Nile tilapia, supporting its therapeutic use in aquaculture. However, proper dosing and strict regulation of withdrawal periods are essential to minimize the risk of antimicrobial resistance.

Dhaka Univ. J. Biol. Sci. 35(2), 111-123, 2026 (July)